Various disc cartridges have been proposed as protective cases for a disk-shaped data storage medium having a single or double data storage sides (which will be herein referred to as a “disc” simply).
For example, Japanese Laid-Open Publication No. 9-153264 discloses a disc cartridge in which a disc is completely enclosed in a disc storage portion. The disc storage portion is defined inside of a cartridge body that is made up of upper and lower halves. The cartridge body includes chucking holes and a head access window. The chucking holes allow the turntable of a spindle motor and a clamper to chuck a disc inserted, while the head access window allows a head to read and/or write data from/on the disc. The lower one of the chucking holes is continuous with the head access window. Accordingly, while the operator carries such a cartridge, dust easily enters the inside of the cartridge through these openings and the disc is also easily soiled with finger marks. For that reason, the disc cartridge further includes a shutter for closing these openings up.
A disc cartridge having such a structure, however, has the following drawbacks. Firstly, such a disc cartridge cannot be so thin. This is because the disc storage space, defined between the upper and lower halves, should be thick enough to allow a disc drive to accurately read or write a signal (or information) from/onto the disc stored in such a disc cartridge. The reasons why the disc storage space should be relatively thick include the expected flutter or warp of the disc being rotated and an error that may occur in disposing the disc cartridge at a predetermined position inside of the disc drive.
Secondly, the shutter for closing up these chucking and head access windows at the same time cannot be formed at a low cost, thus increasing the overall manufacturing cost of such a disc cartridge. The reason is as follows. Specifically, the lower half of the disc cartridge is provided with a hole for the turntable of the spindle motor and a head access window, while the upper half thereof is provided with another hole for the clamper. Thus, to close these three openings up at a time, the shutter needs to be formed in a U-shape with a rectangular bottom, which is not so cheap to make.
Thirdly, the disc stored in such a disc cartridge is not fixed in many cases, thus possibly causing dust or fine particle deposition and scratching problems. Specifically, although a disc with a metal hub can be attracted and fixed in position with a magnet, for example, in a disc cartridge so as not to move inconstantly, an optical disc with no hub, e.g., a CD or a DVD, is normally not fixed, but movable freely, in the disc cartridge. Accordingly, if the disc is shaken so much as to contact with the inner walls of the disc cartridge, the data storage side of the disc may get scratched or fine particles may be stirred up and deposited on the disc.
Furthermore, as the shutter is supposed to open or close linearly, the cartridge body needs to be much bigger than the disc to be stored there. If such a disc cartridge is used to store a small-sized disc for a mobile electronic device or a disc camcorder, for example, then the mobile electronic device or the disc camcorder itself must be big enough to house that disc cartridge. In addition, the size of the head access window of a small-sized cartridge is normally different from that of the head access window of a large-sized cartridge. Accordingly, it is difficult to provide a disc drive that can accept both the small-sized and large-sized cartridges. Or at least the structure of such a disc drive becomes overly complicated so as to accept discs of both types.